(a) Field of the Invention
The present invention is related to an improved structure of a backpressure mechanism of scroll type compressor (STC), and more particularly, to one that prevents compression coolant leakage.
(b) Description of the Prior Art
Referring to FIGS. 1(A) and 1(B) of the accompanying drawings for a sectional view of a structure among a casing 10, an orbiting scroll 20 and a fixed scroll of a scroll type compressor generally available in the market, the compressor is provided with a backpressure mechanism of the prior art. The compressor essentially works inside the casing 10 by having the orbiting scroll 20 to revolve around the fixed scroll 30. Multiple compression chambers 40 with increased pressure inwardly chamber by chamber as the orbiting scroll 20 revolves around the fixed scroll 30 thus to change the volume of the compression chamber 40 to compress the coolant.
Wherein, the compressed coolant enters into a high-pressure chamber 11 provided in the upper space inside the casing 10 through a central compression chamber 40 of the fixed scroll 30. A ring groove 32 is provided on the outer circumference of a coolant passage 31 at the center of the top of the fixed scroll 30. A bypass pore 33 connected through the compression chamber 40 is provided at the ring groove 32 and a ring 51 is provided at the ring groove 32. A sealing device 60 is separately provided at where the ring 51 and the ring groove 32 are inserted into each other. A ring seat 52 is locked to the center of the ring 51 to press against a separation block 12 disposed below the high-pressure chamber 11, and the sealing device 60 is provided between the ring seat 52 and the ring 51 to define a backpressure mechanism.
The purpose of the backpressure mechanism is to guide partial pressure through the bypass pore 33 into the ring groove 32 while the compressor is running so to push up the ring 51 and the ring seat 52 to further increase the air tightness of the fixed scroll 30 and the separation block 12 for preventing leakage of the compression coolant.
The prior art disclosed above relates to a backpressure mechanism taught in USA Patent Publication Re. 35,216; wherein, both of the ring seat 52 and the ring 51 are adapted in the ring groove 32 at the same time. When the pressure in the medium pressure area of the compressor is greater than that in the high-pressure chamber, the sealing device 60 alone fails to reach complete sealing results, thus to form a leakage passage as illustrated in FIG. 1(B) permitting the coolant in the medium pressure area of the ring groove 32 to leak to the high-pressure chamber 11.
Furthermore, the losing of its intended air-tightness function of the sealing device 60 as the compressor is running, the high pressure in the coolant passage 31 escapes to the medium pressure area in the ring groove 32, resulting in abnormal rise of pressure in the medium pressure area and the power to push the fixed scroll becomes significantly higher than that as designed. Consequently, the operation efficacy of the entire backpressure mechanism is discounted, and the compressor efficiency compromised if not failed.